GF40.15-P-0001RU Tire Pressure Monitor Function

GF40.15-P-0001RU Tire pressure monitor function
- with CODE (470) Tire pressure monitor (base)
- with CODE (494) USA version
- except CODE (498) Japan version
- as of 1.7.05 up to model year 08

Component Identification:

General
The tire pressure monitor (TPM) assists the driver in constantly monitoring the correct tire inflation pressure and thus serves active safety.

For this purpose, tire inflation pressure and tire temperature are measured in the tire at certain intervals and transmitted by telemetrics to the TPM [RDK] control unit via a HF transmission path.

Via the left multifunction display (A1p13) in the instrument cluster (A1) the driver is informed about necessary corrections to the tire inflation pressure and about flat tires.

Preventative safety is increased by the TPM system:
^ Tire bursts due to excessive flexing energy and driving quickly with too low air pressure are avoided.
^ The driver is requested to check the tire inflation pressure.
^ A timely warning ensues in the event of a rapid pressure drop (pressure drop greater than 0.2 bar/minute).
^ Regular checking of tire inflation pressure is simplified.

A sudden tire pressure drop cannot be detected by the TPM system.

Working life and economy
Tire wear and fuel consumption are reduced by having the correct tire pressure.

The TPM system does not relieve the driver of the duty to make a regular manual check of the tire inflation pressure (at least every 14 days). In the process the correct tire inflation pressure must be adjusted by means of the table in the fuel filler flap. The TPM system does not warn against an incorrectly adjusted tire inflation pressure.

The TPM system consists of the following components:
^ Central TPM [RDK] antenna (A2/97)
^ Left front tire pressure monitor sensor (A69/1)
^ Right front tire pressure monitor sensor (A69/2)
^ Left rear tire pressure monitor sensor (A69/3)
^ Rear right tire pressure control wheel sensor (A69/4)
^ TPM [RDK] control unit (N88)
^ Scroll forward/back button (S110s1)
^ Buttons + and - for setting specific functions and volume control (S111s1)

Function
The TPM wheel sensors are attached to the metal valves on the rims, are not visible from outside, and measure the air pressure in the tires and the tire temperatures.

The signals are received by the central TPM [RDK] antenna and are relayed to the TPM [RDK] control unit via a discrete cable.

While driving the left front, right front, left rear and right rear TPM [RDK] wheel sensors transmit three data telegrams every 60 seconds. These data telegrams transmit the absolute pressure, the tire temperature, the acceleration, the ID and status information on the manufacturer, frequency, pressure range etc.

The measuring range of the TPM wheel sensor extends from 0 to 5.5 bar (relative pressure).

The ID serves the purpose of detecting the wheels fitted to the vehicle and not of ascertaining the location (e.g. left front).

The TPM [RDK] control unit is permanently operational. Each time the CAN-B (Controller Area Network bus class B (interior)) is alerted by a vehicle start or ignition "ON" (circuit 15), the TPM [RDK] control unit performs a reinitialization and starts to transmit signals to the instrument cluster.

In the TPM [RDK] control unit the air pressure, set and activated by the driver, of each tire is stored as the specified pressure to be monitored.

The data evaluated by the TPM [RDK] control unit is displayed in the multifunction display of the instrument cluster in the form of messages relevant to function and operation.